using System;

using Microsoft.Extensions.DependencyInjection;

​

interface IFooable

{   

}

​

class Foo : IFooable

{

}

​

interface ISomeHelper<T> where T : IFooable

{

}

​

class SomeHelper<T> : ISomeHelper<T> where T : IFooable

{

}

​

class SomeService

{

    // Instead of specifying <Foo> each time I refer to this helper (which happens in quite a few places)

    private readonly ISomeHelper<Foo> _someHelper;

    // I'd rather simplify things and introduce a new type, e.g ISomeDefaultHelper

    private readonly ISomeDefaultHelper _someDefaultHelper;

}

​

interface ISomeDefaultHelper : ISomeHelper<Foo>

{

}

​

static class Extensions

{

     static IServiceCollection AddServices(this IServiceCollection services)

    {

        // However, this doesn't fly:

        services.AddSingleton<ISomeDefaultHelper, SomeHelper<Foo>>();

        return services;

    }

}

​

​

​

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}